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| author |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-07-25 11:21:47 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-09-16 10:07:59 -0700 |
| commit | f4579fc57cf4244057b713b1f73f4dc9f0b11e97 (patch) | |
| tree | 7c682f8da323a07e5a6d63ad4ff87cc1baf34e73 /include/linux/rcupdate.h | |
| parent | rcu: Make nocb leader kthreads process pending callbacks after spawning (diff) | |
| download | linux-dev-f4579fc57cf4244057b713b1f73f4dc9f0b11e97.tar.xz linux-dev-f4579fc57cf4244057b713b1f73f4dc9f0b11e97.zip | |
rcu: Fix attempt to avoid unsolicited offloading of callbacks
Commit b58cc46c5f6b (rcu: Don't offload callbacks unless specifically
requested) failed to adjust the callback lists of the CPUs that are
known to be no-CBs CPUs only because they are also nohz_full= CPUs.
This failure can result in callbacks that are posted during early boot
getting stranded on nxtlist for CPUs whose no-CBs property becomes
apparent late, and there can also be spurious warnings about offline
CPUs posting callbacks.
This commit fixes these problems by adding an early-boot rcu_init_nohz()
that properly initializes the no-CBs CPUs.
Note that kernels built with CONFIG_RCU_NOCB_CPU_ALL=y or with
CONFIG_RCU_NOCB_CPU=n do not exhibit this bug. Neither do kernels
booted without the nohz_full= boot parameter.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Diffstat (limited to 'include/linux/rcupdate.h')
| -rw-r--r-- | include/linux/rcupdate.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index d231aa17b1d7..cc7bed1c90dc 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -269,6 +269,14 @@ static inline void rcu_user_hooks_switch(struct task_struct *prev, struct task_struct *next) { } #endif /* CONFIG_RCU_USER_QS */ +#ifdef CONFIG_RCU_NOCB_CPU +void rcu_init_nohz(void); +#else /* #ifdef CONFIG_RCU_NOCB_CPU */ +static inline void rcu_init_nohz(void) +{ +} +#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ + /** * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers * @a: Code that RCU needs to pay attention to. |